This invention relates to a fire-fighting turret or monitor, or similar fluid-projecting device, which is mounted in a fixed position but can be aimed in any direction and at any elevational angle by rotating a pair of swivelable joints disposed at an acute angle to each other.
This application claims the benefit of provisional application Ser. No. 60/213,016 filed Jun. 21, 2000 and entitled xe2x80x9cA New Design for Fire-fighting Water Turrets, or Monitorsxe2x80x9d.
In fire fighting and other applications, water turrets or monitors are used to direct a stream of water. Generally these monitors are controlled by a manual operator who maneuvers a handle or other mechanically linked device, or by an operator who remotely controls the action of the monitor through hydraulic or electric links or a combination thereof. Such monitors can also be operated and activated automatically, as for example by a fire detector or timed circuit.
It is desirable to make such turrets cover an area with a volume of water by appropriately moving the nozzle continuously or intermittently to aim the water stream in different directions. In general, the positional variables of the monitor include the elevation and azimuth in which the nozzle is pointing or spraying. Thus terms like Left, Right, Up and Down are used to label the positional turret controls and describe the motion of the stream.
As the state of the art has evolved from handheld hoses and nozzles to the manually operated turrets, and on to the remotely controlled and automatic monitors discussed above, there has been a tendency to add onto current methods without going back to the primary function to be served and creating a product from the ground up. Thus the axes necessary to create independent left-right and up-down actions were maintained without change from the hose to the monitor to the remote-controlled monitor. In addition, each of the axes or joints could be held against unintended movement by a mechanical device such as a friction lock or a pin in a hole. Automating merely meant adding electrical, mechanical or hydraulic actuators to the joints and swivels that were used in the mechanically controlled units. To gain the torque necessary to control the joints and to supply the static friction required to hold the nozzle in place when not being moved in one of the axes, a combination of gears including a worm gear was generally used.
Several general models of monitors have been devised to create the ability to sweep through the necessary range. One of these is a re-converging stream in which the water generally passes through a pipe that swivels to create the left-right rotation and coverage, then splits roughly equally and directs the water through separate symmetric pipes into flows which are perpendicular to the first swivel. This allows for a second set of swivels to provide the up-down coverage. Then the water is re-converged into a single stream and sent through a nozzle as desired. This model requires several complex cast components. Splitting the water into two pipes, forcing it through a quick series of sharp bends, then recombining the two streams which are running in almost opposite directions creates turbulence, back pressure and pressure losses that are detrimental to the water flow.
Another model can be thought of as a series of bent tubes. In this traditional configuration the water stream is forced over 45xc2x0 of bends, with one bend being a 180xc2x0 bend causing the stream to flow twice as far and twice as fast on the outside of the bend as the water on the inside of the bend. This geometry also creates turbulence and pressure drops that are adverse to the final stream pattern.
A third model is a tighter version of the bent tube design created by using castings. This allows for a tighter geometry but exaggerates the turbulence of flow speed differentials. In order to combat these problems, this design is forced to increase the cross-sectional area of the joint areas, which increases turbulence and forces acting on the joints. Even internal flow straightening vanes cast into the waterways to combat these deficiencies have the adverse effect of causing additional surface drag.
When these designs were automated to allow for operator control through switches or a joystick, or to allow for automatic operation in a preset manner without input from an operator, gearing and actuators such as electric and hydraulic motors were added on top of existing designs.
The present invention overcomes the problems of the prior art by providing a monitor or turret using a single curved tube with three mutually rotatable sections. The sections are separated by two swivelable joints whose axes are at an acute angle (e.g. 45xc2x0) to each other. The axes of the joints are interdependent, i.e. rotation of one joint changes the axial or angular orientation of the other joint. By concurrently rotating both joints, the nozzle can be aimed at any point within more or less a hemisphere centered on the monitor.
In accordance with one aspect of the invention, the joints are preferably rotated by a direct electric or hydraulic drive or servo motor in which the static position of the monitor is maintained electrodynamically or electromechanically. A microprocessor control computes and executes the appropriate motion of each joint to obtain a nozzle orientation having a desired bearing and azimuth within the monitor""s hemisphere.
In the joint mechanism of this invention, the fundamental components of the joints and bearings are part of the waterway formed by the curved tube. The geometry of the joints is such that the water stream at each joint is always coaxial with that joint so as to eliminate any water-caused torque on the joint and drive. The geometry of the monitor is such that a full forwardly extending hemisphere ahead of a fire truck can be covered by a monitor mounted on a horizontal pipe on the front of the truck without requiring a 90xc2x0 bend for vertical mounting. Alternatively, the inventive monitor can cover an entire upwardly extending hemisphere centered on the truck if mounted vertically.